The lowlatency kernel will eventually undergo deprecation. Rather than
wait for such a time to happen and be reactive, Ubuntu Studio would
rather be proactive about this now that the generic kernel can act as a
lowlatency kernel with certain command line parameters as outlined by
https://discourse.ubuntu.com/t/fine-tuning-the-ubuntu-24-04-kernel-for-low-latency-throughput-and-power-efficiency/44834.
As such, we have modified our `ubuntustudio-lowlatency-settings`
package, which installs `/etc/default/grub.d/ubuntustudio.cfg` with the
following line:
-GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT threadirqs"
+GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT preempt=full
nohz_full=all threadirqs"
Additionally, that same file used to set "GRUB_FLAVOUR_ORDER" which is
no longer needed.
The ubuntu-core-installer image is an installer that installs ubuntu
core. The environment the installer runs in is similar to the server
installer but it has a source catalog entry that points to the model
created in ubuntu-core-installer/hooks/05-prepare-image.binary, which
subiquity knows how to install.
The LXD snap is no longer seeded in any images since Noble+ so the LXD related unminimize logic in
./live-build/auto/build?h=ubuntu/noble and ./live-build/ubuntu-server/hooks/01-unminimize.chroot_early
is no longer required.
lxd-installer can remain installed.
do_layered_desktop_image() is now the standard entry point for flavors using
ubuntu-desktop-bootstrap and handles minimal/standard/live layers in a
configurable and flavor-agnostic way to reduce code duplication.
ubuntu/include.* are the master location for these files.
Copy them over for projects with similar needs, while skipping ones that
are incorrect.
LP: #2055077
Ubuntu MATE is switching to a layered image in preparation to
use ubuntu-desktop-provision. Luckily, their seed structure is
already well-structured for layering, so this is easily done.
This has become moot now that the code block has been
moved out from live-build/functions to live-build/auto/build
so passing the argument is not needed anymore.
Presence of this field helps in determining if the image is an
unminimized image, which then can be leveraged in the unminimize
script to easily determine the image type.
Per the comments, BASE_SEED was initially used to identify the seed in the
flavor to use for identifying preseeded snaps, and later was also used to
identify which "minimal-remove" seed to apply to an image.
The first usage is now obsolete after a refactor; we now correctly detect
snaps from any of the included seeds without needing an explicit
declaration.
The second usage only applies to installer images that are NOT using layered
squashfs, since for these images 'minimal' is a separate squashfs layer
rather than a list of packages to remove after the fact.
Refactor this code to eliminate pointless definitions of BASE_SEED and
define it only for the subset of flavors today that:
- have a 'minimal-remove' seed
- are not using layered squashfs.
